Hitherto, when laminating a printed layer on a surface of an ABS resin film, a transfer film comprising a PET film and the printed layer previously provided on a surface of the PET film is thermally laminated on the ABS resin film, and then the PET film is peeled off therefrom to transfer the printed layer on the ABS resin film (refer to Patent Document 1). The reason therefor is that the ABS resin film is not directly subjected to printing owing a poor solvent resistance thereof. However, in the above conventional printing method using the transfer film, since the transfer film must be subjected to the peeling step after transferring the printed layer, there tend to arise the problems such as complicated production process, increase in costs owing to disposal of the transfer film as waste, and risk of inclusion of foreign matters into the resulting laminate during the production process.
On the other hand, it will be considered that the surface of the ABS resin film is subjected to corona treatment to form an anchor coat layer thereon, and then the printed layer is formed on the anchor coat layer (refer to Patent Documents 2 and 3). However, in this printing method, since the additional step of forming the anchor coat layer is required, the production process tends to become complicated. Therefore, it has been demanded to provide a method of directly forming the printed layer on the ABS resin film.
Also, when thus forming the printed layer on the resin film and then thermally laminating a transparent resin layer such as an acrylic resin layer on the printed layer, the resin film is required to have sufficient heat resistance, mechanical strength and dimensional stability, etc. However, the conventional ABS resin film may fail to exhibit these properties to a sufficient extent.
In addition, upon formation of the above resin film, there tends to occur such a problem that the resin film is hardly released from a roll (for example, cast roll or cooling roll) and lifted therefrom while being kept adhered thereto, so that the resulting resin film tends to have a poor appearance. In particular, the above problem tends to become more remarkable in the case where the film-forming temperature (roll temperature) is raised to obtain a film having an excellent heat resistance.    Patent Document 1: Japanese Patent Application Laid-Open (KORAI) No. 2005-178276    Patent Document 2: Japanese Patent Application Laid-Open (KORAI) No. 2007-210309    Patent Document 3: Japanese Patent Application Laid-Open (KORAI) No. 2007-211219